Hello Daniel,
[...] So psql is not following that model with ON_ERROR_STOP if it exits
with an error when unable to evaluate an "if" expression. I'm not
implying that we should necessarily adopt the shell behavior, but as
these choices have certainly been made in POSIX for good reasons, we
should make sure to think twice about why they don't apply to psql.
Interesting point.
The shell is about processes, and if relies on the status code returned,
with 0 meaning true, and anything else, which is somehow a process error,
meaning false. So there is no way to distinguish false from process error
in this system, because the status is just one integer.
However, a syntax error, for instance with a shell internal test, leads to
nothing being executed:
bash> if [[ bad syntax ]] ; then echo then ; else echo else ; fi
-bash: conditional binary operator expected
-bash: syntax error near `syntax'
# nothing is echoed
Another example with python in interactive mode:
python> if 1+: print 1; else print 0
SyntaxError: invalid syntax
# nothing is printed
So rejecting execution altogether on syntax errors is somehow a common
practice.
--
Fabien.
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